Explosive charge



Patented Got. 2, 1934 UNITED STATES EXPLOSIVE CHARGE Philip G. Wrightsman, Chester, Pa., assignor to E. I. du Pont de Nemours & Company, Wilmmgton, Del., a corporation of Delaware No Drawing. Application June 1'7, 1932, Serial No. 617,879

10 Claims.

This invention relates to an improved explosive charge for initiators, shells, bombs, blasting caps, and for like purposes, and more particularly to an improved cast explosive charge having desir- 5 able properties, especially from the point of view of ease of loading.

In the manufacture of blasting caps, the usual practice is to press into a metal shell 2. main or base charge of explosive at a pressure of approximately 300 kg. per sq. cm. and to follow this with a priming charge subjected to a pressure of 250 kg. per sq. cm. Explosives commonly used as base charges in the past have been tetryl trinitrotoluene, pentaerythritol tetranitrate, picric acid,

5 and like compounds. The most commonly used priming charges have been mercury fulminate and lead azide.

From the point of view of explosive strength of detonator or projectile, it is desirable that the ex- 0 plosive charge have as high a density as practical.

This density may be increased by the use of greater charging pressures. The pressure that can be used, however, is limited by the amount the shell wall will stand.

Eschbach has described a method of making high density base charges (British'Patent 1'72,- 914) by using a specially designed press in which the shell is pressed in a die and subjected to high pressures, for examples 1,000 kg. per sq. cm. from both ends of the shell simultaneously. This procedure, however, requires expensive equipment, and introduces undesirable complications since the pressed shells must later be punched from the die, thus necessitating a separate operation.

The advantages of high charging densities may be obtained with much less expense and less hazard by charging the explosive into the shell or container in liquid form and allowing it to solidify in the shell. This same effect may be obtained also by loading the explosive into the shell in loose, granular form, heating the shell containing the explosive to bring about fusion, and cooling to obtain the high density cast charge.

In order that advantage may be taken of this simple method of obtaining a high density cast charge in detonators or shells, it is necessary that the explosive have a melting point sufficiently under the point of decomposition so that the operation will not be hazardous. While explosives have long been cast for certain purposes, for example in the loading of military shells with explosives such as trinitrotoluene and amatol, the process of casting charges for blasting caps has had little application until recently. The explo- 55 sives now in common use as base charges in blasting caps, such as, tetryl, and the like, have, in f general, high melting points and are not suitable for casting.

The object of my invention is an improved cast explosive charge. A further object is such a 6 charge having a melting point sufficiently low so that it is suitable for use as a cast charge for initiators, blasting caps, shells, bombs, and the like. A still further object is a cast charge whose fusion point has been lowered to the desired degree by the addition of one or more explosive compounds to the first compound. Further objects will be disclosed hereinafter.

I have found that these objects are accomplished by incorporating the ethyl homologue of tetryl, that is, trinitrophenylethylnitramine as an ingredient in the explosive charge. This compound, Which may be represented by the formula NOg-N-CHz-CE:

NO N02 is similar in formula to trinitrophenylmethylnitramine (tetryl) and may be obtained by a similar nitration process. 'Irinitrophenylethylnitramine may be obtained by the nitration of ei- 65 ther mono-ethylaniline or di-ethylaniline, while 1 the starting point for tetryl is dimethylaniline.

Trinitrophenylethylnitramine' has the advantage over tetryl, from the point of view of use in cast charges, in that it melts at a lower temperature. Whereas tetryl has a melting point of 129 C., the melting point of the ethyl deriva tive is 96 C.

I may use trinitrophenylethylnitramine alone as a cast charge indetonators. I prefer, however, to use it in combination with another explosive compound, preferably tetryl. By the use of the two compounds, a fusion point results which is lower than the fusion point of either of the separate constituents, according to the well-known laws of physical chemistry. While a mixture of trinitrophenylethylnitramine and tetryl may be prepared by the use of the two different compounds in the desired amounts, after they have been prepared separately by separate nitration procedures, I find it advantageous to obtain a desired blend of the two compounds by the single nitration of a mixture of diethylaniline and dimethylaniline in such proportions that a charge is Obtained consisting of the two nitrated compounds, the mixture having a melting point well within the range suitable'for casting.

In the preparation of such a combined charge, I may take, for example, 150 parts of diethylaniline and parts of dimethylaniline, dissolve these in 2000 to 2100 parts of strong sulfuric acid and add this solution to 1200 to 1400 parts of strong nitric acid. The nitrated product may be recovered by drowning in a large volume of water, washing free from acid with water, and stabilized by recrystallization from a suitable solvent, if so desired. The dry stabilized product, so prepared, will consist of approximately parts of trinitrophenylethylnitramine and 30 parts of trinitrophenylmethylnitramine. This combination will have a melting point of 85 to 88 C. and lends itself readily to the production of a cast explosive charge for detonators.

While I have described the nitration procedure in detail, I do not limit myself to any particular mixture of diethylaniline or dimethylaniline. If desired, monoethylaniline or monometh'ylaniline may be used in place of the above compounds. I do not intend to be limited either to any particular acid strength, acid ratio, or nitration procedure. Any nitration method may be used that will produce a mixture of trinitrophenylethylnitramine and trinitrophenylmethylnitramine suitable for use as a cast explosivecharge.

Similarly, trinitrophenylethylnitramine may be used with pentaerythritol tetranitrate. For example, a mixture comprising 30 parts of pentaerythritol tetranitrate and 70 parts of trinitrophenylethylnitramine will have a melting point of 84 to 87 C., and is adapted for use as a cast explosive charge.

While I have described mixtures of two compounds that are adapted for use together as a cast charge, I find also that mixtures of trinitrophenylethylnitramine with trinitrophenylmethylnitramine may be blended with other explosive compounds for depression of the fusion point. In this way, desirable cast charges may be obtained. For example, I may use a charge consisting of parts of a 50-50 mixture of trinitrophenylethylnitramine and trinitrophenylmethylnitramine with 20 parts of pentaerythritol tetranitrate. This mixture will have a fusion point of 83 to 85 C., and is adapted for use asa cast charge in blasting caps.

While I have cited only a few examples in which trinitrophenylethylnitramine may be used in the production of cast explosive charges, I do not wish to be limited to the mixtures mentioned. It should be understood that all combinations suitable for use as cast charges are included within the scope of this invention, provided trinitrophenylethylnitramine is one of the ingredients. It should be understood also that other methods may be used for loading the charge into the cap or shell. The charge may be first fused then loaded in liquid form; or it may be charged in loose granular form, melted in the container, and then cooled to obtain the cast charge.

In the foregoing, I have described my improved cast charge particularly in connection with its application to blasting cap charges. It is to be understood, however, that it is equally adapted for charges in high explosive shells and bombs, and for all cases where a cast charge of a secondary detonating explosive is required. I intend therefore to be limited in the scope of my inven-- tion only as indicated in the following patent claims.

I claim:

1. A cast explosive charge comprising a fused mixture of trinitrophenylethylnitramine with at least one compound of the group consisting of tetryl and pentaerythritol tetranitrate. V

2. An initiator containing a cast explosive charge comprising a fused mixture of trinitrophenylethylnitramine with at least one compound of the group consisting of tetryl and pentaerythritol tetranitrate.

3. A high explosive shell charge comprising a cast explosive chargeconsisting of a fused mixture oi trinitrophenylethylnitramine with at least one compound of the group consisting of tetryl and pentaerythritol tetranitrate. I

4:. A blasting cap comprising a cast explosive charge consisting of a fused mixture of trinitrophenylethylnitramine with at least one compound of the group consisting of tetryl and pentaerythritol tetranitrate.

5. A blasting cap containing an explosive charge comprising a fused mixture of trinitrophenylethylnitramine and trinitrophenylmethylnitramine.

6. A blasting cap containing an explosive charge comprising a fused mixture of approximately 70 parts of trinitrophenylethylnitramine and approximately 30 parts of trinitrophenylmethylnitramine.

'7. A blasting cap containing an explosive charge comprising a cast mixture of trinitrophenylethylnitramine, trinitrophenylmethylnitraminc, and pentaerythritol tetranitrate.

8. A blasting cap containing an explosive charge comprising a cast mixture of approximately 20 parts of pentaerythritol tetranitrate and approximately 80 parts of a mixture consisting of substantially equal parts of trinitrophenylethylnitramine and trinitrophenylmethylnitramine.

9. A blasting cap explosive charge comprising a fused mixture of trinitrophenylethylnitramine and pentaerythritol tetranitrate.

10. A blasting cap explosive charge comprising a cast mixture consisting of approximately 70 parts trinitrophenylethylnitramine and approximately 30 parts pentaerythritol tetranitrate.

PHILIP G. WRIGHTSMAN. 

